The field of this invention relates generally to radio frequency (RF) modules for wireless communication units and more particularly to RF transceiver front end modules capable of supporting self-calibration.
Wireless communication units, e.g. portable radios, telephones, etc., conventionally supported operation in a single radio frequency (RF) band, i.e. the operational band employed by the communication system. However, due to the rapid growth of mobile communications, there has been a comparable increase in the amount of spectrum that is required to support the various radio frequency standards, systems and services that are now available to mobile users. Consequently, as radio frequency (RF) communication systems have evolved, there has been a recent trend for mobile communication devices to support communications in a plurality of RF bands, for example to support communications across a plurality of communication standards or geographical regions. Currently, a typical transceiver adapted to support communication within, for example, a Universal Mobile Telecommunications System (UMTS) may be required to support more than ten distinct frequency bands.
FIG. 1 illustrates a simple block diagram of a typical mobile (wireless) communication unit (sometimes referred to as a mobile subscriber unit (MS) in the context of cellular communications or a user equipment (UE) in terms of a 3rd generation partnership project (3GPP™) communication system). The wireless communication unit 100 contains an antenna 102 preferably coupled to a duplex filter or antenna switch 104 that provides isolation between receive and transmit chains within the wireless communication unit 100.
The receiver chain, as known in the art, includes receiver front-end circuitry 106 (effectively providing reception, filtering and intermediate or base-band frequency conversion). The receiver front-end circuitry 106 is serially coupled to a signal processing function 108. A controller 114 is also coupled to the receiver front-end circuitry 106 and the signal processing function 108 (generally realised by a digital signal processor (DSP)). The controller 114 is also coupled to a memory device 116 that selectively stores operating regimes, such as decoding/encoding functions, synchronisation patterns, code sequences, and the like.
As regards the transmit chain, this essentially includes transmitter/modulation circuitry 122 and a power amplifier 124 that is operably coupled to the antenna 102. The transmitter/modulation circuitry 122 and the power amplifier (PA) 124 are operationally responsive to the controller 114. A coupler 110 is located between the PA 124 and the antenna switch 104 and arranged to couple off a portion of the signal being transmitted to a feedback path and thereafter to baseband processing circuitry to enable the transmit signal to be optimised to the prevailing conditions of the wireless communications unit and/or the prevalent radio conditions, e.g. optimising a power control of the transmitted signal based on the vicinity of a receiving communication unit.
However, the cost of supporting a wide frequency range covering many frequency bands or communication standards in such a wireless communication unit is that many parallel transceiver circuits are required to fit within the wireless communication unit and/or one or more of the parallel transceiver circuits needs to be tuneable to operate across multiple frequency ranges. A number of adverse effects follow from either of these solutions within the wireless communication unit, including requiring higher quality of RF components that consume either significant amounts of silicon area or module board area. Furthermore, these solutions also increase design complexity in order to meet performance requirements simultaneously over all the supported frequency bands.
Thus, a need exists for an improved architecture and method of operation therefor that supports multiple frequency ranges and/or multiple communication standards.